Mechanism for rapping the collecting electrodes in electrostatic precipitators



Nov. 23, 196 w. STEUERNAGEL ETAL 3,219,130

MECHANISM FOR RAPPING THE COLLECTING ELECTRODES IN ELECTROSTATICPREGIPITATORS Filed July 1, 1963 3 Sheets-Sheet l Inventor's (Multan; Stemezwa el wait-e1 egb L 3, 1965 w. STEUERNAGEL E'l"AL 3,219,130

MECHANISM FOR RAPPING THE COLLECTING ELECTRODES IN ELECTROSTATICPRECIPITATORS 3 Sheets-Sheet 2 Filed July 1, 1963 fm/emars N v. 3, 1965w. STEUERNAGEL ETAL 3,219,130

MECHANISM FOR RAPPING THE COLLECTING ELECTRODES IN ELECTROSTATICPREGIPITATORS Filed July 1, 1963 3 Sheets-Sheet 5 United States Patent 3219,130 MECHANISM FOR RAPPING THE COLLECT- ING ELECTRODES INELECTROSTATIC PRECIPITATORS Walter Steuernagel and Walter Biibel,Frankfurt am Main,

Germany, assignors to Metallgesellschaft Aktiengesellschaft, Frankfurtam Main, Germany Filed July 1, 1963, Ser. No. 291,932 Claims priority,application Germany, July 6, 1962, M 41,833 4 Claims. (Cl. 173-102) Thisinvention relates to a mechanism for rapping the dust collectingelectrode plates in electrostatic precipitators.

For effectively cleaning off the deposited dust from the electrodeplates in electrostatic precipitators, it is the practice to apply asequence of raps of different strengths at controllably variableintervals to the rapper bar which is common to a plurality of electrodeplates. The power required for producing the raps is usuallyelectromagnetically generated, whereby the intensity of the raps andtheir frequency are controlled by electronic means. This is describedfor instance in Combustion, July 1960, pages 5 and 6.

In order to maintain the dust collection efiiciency of the electrostaticprecipitator, the collecting electrode plates must be kept substantiallyfree from adhering deposits of dust. Large volumes of gas containinghigh concentrations of dust precipitate considerable volumes of dust onthe collecting electrode plates within a very short time. In order toprevent the cleaning operation from swirling the dust back into the gasstream, it is advisable to rap the electrode plates in such a way thatthe dust will detach itself from said plates in large flakes and fallinto the dust box without raising a cloud. This can be achieved byapplying gentle raps. However, thin layers of dust always remain on theelectrode plates which refuse to be detached by gentle raps and whichthen continue to reduce the dust collection efiiciency of the plates.These coatings of dust cannot be removed otherwise than by theapplication of hard raps to the plates. It is therefore the practice toclean oil the dust from the plates by applying raps of increasingintensity, and this will then avoid the dust from being whirled up inclouds. Although mechanical rapping is preferable to rapping the plateselectromagnetically because mechanical rapping devices are of simplerconstruction and more reliable, and the rapping devices may be locatedinside the dust chamber and will then readily collect dust themselves,efiicient mechanical rapping devices for applying variable intensityraps have not heretofore been made. An object of the present inventionis to provide a mechanism which satisfies this particular need.

According to the present invention, there is provided a mechanism forrapping collecting electrode plates in electrostatic precipitators bythe application of raps to an end of a rapper bar by means of at leasttwo tumbling or somersaulting hammers, wherein the hammers are ofconsecutively increasing weight and are eccentrically mounted on thesame axis of a rotary member in such manner that rotation of the rotarymember causes the hammers to rap the rapper bar such that a series ofraps is produced each consisting of a number of raps of increasingintensity.

The mechanism has tumbling hammers which are of a spherical or acylindrical disc-like shape so arranged that each tumbling hammer isattached to a movable arm and adapted to strike centrally the rear faceof the preceding hammer which has already struck the rapper bar.

Alternatively, the tumbling hammers have a cube or 3,219,130 PatentedNov. 23, 1965 brick shape, and only one side of the hollow cube orbrick, which may lack a bottom, top and rear face, may form a hammerface so contrived that consecutively operating hammers can strike theback of the preceding hammer face, one hammer fitting into the other. Inthis way, the entire impact can be directly transferred to the rapperbar wi'hout loss of a lateral component of momentum.

A further modified form of this invention is composed of a spring-urgedrapping bar, and means for moving the rapping bar against the spring forat least two distances, and subsequently releasing the rapping bar sothat the latter effects the rapping of the electrode plates under theinfluence of the spring, the intensity of the rap being proportional tothe distance moved by the rapping bar against the spring, and thearrangement being such that a series of raps is produced each consistingof a number of raps of increasing intensity.

Another modified form of this invention has the rapping bar moved by arotating cam having at least two extensions each being of differentlength and arranged so that rotation of the cam causes the extensions inturn to bear upon upon a plate fixed to or integral with the rapping barand thus move the bar against the pressure of the spring.

The means by which the objects of this invention are obtained aredescribed more fully with reference to the accompanying diagrammaticdrawings in which:

FIGURES 1, 2 and 3 are side views showing one embodiment of a mechanismconstructed in accordance with the invention in successive positions;

FIGURE 4 is a side view showing another embodiment of this invention;

FIGURE 5 is an end view of the mechanism shown in FIGURE 4;

FIGURE 6 is a view similar to FIGURE 4 showing the hammer in anotherposition; and

FIGURE 7 is a cross-sectional view showing a further embodiment of thisinvention.

As shown in FIGURES 1, 2 and 3, two rapping weights or hammers 1 and 2in the form of spheres or cylindrical heavy discs of which disc 1 islighter than 2 are rotatably attached by arms 3 and 3, respectively, toan eccentric pivot pin 4 on a crank 5, which is itself fixed to a shaft6 for driving the same. Moreover, the outer member of the divided arm 3'has a joint 7 including an elongated slot 8 where the joint is formed,permitting either or both the angular setting of the outer member andthe overall length of the arm to be varied. In FIGURE 1, the rotatingcrank has lifted both weights to the point where weight 1 is just readyto fall. FIGURE 2 shows the moment when the minor weight 1 has juststruck the rapper bar 9. FIGURE 3 shows how the further rotation ofcrank 5 causes the heavier weight to fall.

In the modified form of construction shown in FIG- URES 4, 5 and 6, twohammers 10 and 11 are brick-like or eccentric in shape. The lighterhammer 10 is composed of two lateral members as well as a hammer face 12which can be struck by the second heavier hammer 11. Hammer 11 fits intohammer 10 and against hammer face 12 both for striking and lifting thesame. In this latter position, the two sets of hammer arms 13 and 13'which are both hinged to the same pivot pin 14 will be in full alignmentwhen viewed from the side. This arrangement has the advantage thatsupplementary weights 10', which can be clearly seen only in FIGURE 5,can be attached to the outer sides of the lateral members of hammer 10.The functions of crank 5 in FIGURES 1, 2 and 3 are performed in FIGURES4, 5 and 6 by a strap 15 clamped to shaft 16. Naturally the strap 15could be replaced by a suitable alternative means of attachment, such asa wide lug or a tie bolt.

For the sake of simplicity only two rapper hammers are shown in the twoembodiments described above, but preferably there should be three.

In the modification of FIGURE 7, different intensity raps are generatedby means of a rapper bar 17 outwardly displaceable from a centerposition. A casing 18 encloses the rapper mechanism which comprises aspring 20 embracing the reduced end 17' of the rapper bar 17. A cammember 21 which revolves together with shaft 22 has two finger-shapedextensions 23 and 24 adapted to bear consecutively against theprojecting cross member 25 on rapper bar 17, the short finger, by urgingthe bar against the compression spring, generating a Weaker rap and thefollowing longer finger 24, by urging the bar a greater distance andthus more strongly compressing the spring, generating a much morepowerful rap. The lower part 19 of the box 18 is detachable and filledwith a protective liquid 26, preferably oil.

The described mechanism permits electrical and electromagnetic rapperelements or vibrators to be dispensed with and raps of graduated powerto be generated by mechanical means for cleaning off the collectingelectrode plates without whirling up dust.

Having now described the means by Which the objects of this inventionare obtained, we claim:

1. Mechanism for rapping collecting electrode plates in electrostaticprecipitators by the application of hammer raps to an end of a rapperbar engageable with said plates, comprising a rapper bar, a rotarydriving member, at least two tumbling hammers, said hammers being ofconsecutively increasing weight means mounting said hammers on the sameaxis eccentrically joined to said rotary driving member in such mannerthat rotation of the rotary driving member causes a light hammer tofirst hit said bar and a following heavier hammer to then hit said firstlight hammer so that the hammers rap the rapper bar with a series ofraps each consisting of a number of raps of increasing intensity.

2, Mechanism as in claim 1, said tumbling hammers being of spherical orcylindrical disc-like shape, and said means mounting said hammerscomprising movable arms joined to said hammers for said heavier hammercentrally striking the rear face of the preceding hammer which hasalready struck the rapper bar.

3. Mechanism as in claim 2, further comprising means for increasing theweight of at least one of the hammers. one of the movable arms.

4. Mechanism as in claim 3, further comprising means for increasing theweight of at lease one of the hammers.

References Cited by the Examiner UNITED STATES PATENTS 651,320 6/1900Albree 173-102 X 1,115,782 11/1914 Christiani 173102 X 1,551,724 9/1925Anderson -110 X 1,744,802 1/1930 Rock 173-102 X 2,123,473 7/1938 Meston55148 X 2,706,618 4/1955 Boucher 173--101 X 2,812,035 11/1957 Sohlman eta1 55148 X 2,864,459 12/1958 Gustafsson 55--135 X 3,083,081 3/1963 Sharpet al. 3485 X 3,113,852 12/1963 Steuernagel 55148 X FOREIGN PATENTS756,671 9/ 1933 France.

467,410 10/ 1928 Germany.

469,652 12/1928 Germany.

496,061 4/ 1930 Germany.

505,795 8/ 1930 Germany.

OTHER REFERENCES German application 1,108,667, Haberle et al., printedJune 15, 1961.

BROUGHTON G. DURHAM, Primary Examiner.

ROBERT F. BURNETT, Examiner.

1. MECHANISM FOR RAPPING COLLECTING ELECTRODE PLATES IN ELECTROSTATICPRECIPITATORS BY THE APPLICATION OF HAMMER RAPS TO AN END OF A RAPPERBAR ENGAGEABLE WITH SAID PLATES, COMPRISING A RAPPER BAR, A ROTARYDRIVING MEMBER, AT LEAST TWO TUMBLING HAMMERS, SAID HAMMERS BEING OFCONSECUTIVELY INCREASING WEIGHT MEANS MOUNTING SAID HAMMERS ON THE SAMEAXIS ECCENTRICALLY JOINED TO SAID ROTARY DRIVING MEMBER IN SUCH MANNERTHAT ROTATION OF THE ROTARY DRIVING MEMBER CAUSES A LIGHT HAMMER TOFIRST HIT SAID BAR AND A FOLLOWING HEAVIER HAMMER TO THEN HIT SAID FIRSTLIGHT HAMMER SO THAT THE HAMMERS RAP THE RAPPER BAR WITH A SERIES OFRAPS EACH CONSISTING OF A NUMBER OF RAPS OF INCREASING INTENSITY.